ens, it appeared to me that an appropriate and
interesting subject might be the present and future problems of
astronomy. Yet it seemed, on further reflection, that, apart from the
difficulty of making an adequate statement of these problems on such an
occasion as the present, such a wording of the theme would not fully
express the idea which I wish to convey. The so-called problems of
astronomy are not separate and independent, but are rather the parts of
one great problem, that of increasing our knowledge of the universe in
its widest extent. Nor is it easy to contemplate the edifice of
astronomical science as it now stands, without thinking of the past as
well as of the present and future. The fact is that our knowledge of
the universe has been in the nature of a slow and gradual evolution,
commencing at a very early period in human history, and destined to go
forward without stop, as we hope, so long as civilization shall endure.
The astronomer of every age has built on the foundations laid by his
predecessors, and his work has always formed, and must ever form, the
base on which his successors shall build. The astronomer of to-day may
look back upon Hipparchus and Ptolemy as the earliest ancestors of whom
he has positive knowledge. He can trace his scientific descent from
generation to generation, through the periods of Arabian and medieval
science, through Copernicus, Kepler, Newton, Laplace, and Herschel,
down to the present time. The evolution of astronomical knowledge,
generally slow and gradual, offering little to excite the attention of
the public, has yet been marked by two cataclysms. One of these is seen
in the grand conception of Copernicus that this earth on which we dwell
is not a globe fixed in the centre of the universe, but is simply one
of a number of bodies, turning on their own axes and at the same time
moving around the sun as a centre. It has always seemed to me that the
real significance of the heliocentric system lies in the greatness of
this conception rather than in the fact of the discovery itself. There
is no figure in astronomical history which may more appropriately claim
the admiration of mankind through all time than that of Copernicus.
Scarcely any great work was ever so exclusively the work of one man as
was the heliocentric system the work of the retiring sage of
Frauenburg. No more striking contrast between the views of scientific
research entertained in his time and in ours can be f